Method of manufacturing gas-filled envelopes



Patented Jan. '20," 1931 3 UNITED STATES PATENT. oFF cs RAYMOND ROBERT KACHLETT, Of NEW N. Y., LSSIGNOB TO RAINBOW LIGHT,

' .INQ, A. COR1OBA'1ION O! YORK ammo!) or uaxuraoruame Gas-mun ziwiimmis V Application filed September in, ma sum in. 50,046.

My invention relates to methods of manufacturing gas filled envelopes and parti cularly to the manufacture of circuit" breakers or interrupters for use in high frequency current generators of the oscillatory charge type for energizing. vacuum tube lamps.

In devices of the above type it is highly important that the circuit interruption be as nearly instantaneous as possible to produce the desired rapid rise in potential across the breaker contacts. A further desired quality is that the device be capable of continuous operation for long periods of time of the order of several thousand hours. Principal objects of the present invention are to provide for the manufacture" of the device in a' dependable and relatively simple manner.

Attempts have been made to provide suitable breaker devices for the above purpose by the use of various metals of which tungsten has been found most satisfactory, but even this, when used for breaker points operated in air, oxidizes comparatively rapidly resulting in short life especially where direct current is used, whenwhat is known as pitting takes place, that is, the formation of a int on one contact and a pit on the other, w ich reduces the contact area and ultimately results in the permanent engagement or freezing of the contact points. To avoid oxidation, 'it has been attempted heretofore.

to construct breaker mechanisms for opera-- tion in vacuum. However, such mechanisms depend upon the use ofa steel or other tentred metal spring and therefore will not withstand high temperatures. Consequently, among other difliculties of construction heretofore encountered, the degasification of the.

. parts has been extremely troublesome and inamount of gas in the vacuum tube, whether.

deed commercially impractical. The least residual or evolved during operation, may

be. ionized by the potential use across the breaker points and cause reduction in the vacuuin and; degasification, the efliciency would be low due to the fact that in a high degree of, vacuum there would be, current detail Even with a high degree of leakage during the separation of the breaker points with resultant lack of the desired rise in potential at this time. f '1,

To overcome these difliculties, advantage is taken of the fact that a gas under pressure surrounding a spark gap operates to uench the oscillatory spark, and accordingly t einterrupter contacts are enclosed in an envelope with an inert gas under-pressure. While the use of ordinary atmospheric pressure is not excluded in practicing the invention, it is found that gas at. atmospheric pres sure in an envelope of practical dimensions will ionizein time, tending eventually to lower or destroy the operating efficiency and even ruin the device itself. 'llhe use of a pressure substantially'higher than atmospheric is therefore to be recommended in practice in order to eliminate ionization and most satisfactorily to give the desiredquenching action; It is most desirable that the enclosing envelope or tube be of glass and provided with a welded seal, but usual methods of fabricating sealed glass tubes would not be feasible in the present instance, be cause any attempt to seal off the tube with superatmospheric pressure therein would result in the glass blowing" out and releasing thepressure when softened byheat for sealing. The invention therefore includes a novel method of manufacture whereby production of a sealed-oil glass tube containing the breaker mechanism in an atmosphere ofblan inert gas under pressure becoines possl e. In order more fully to explain the principles of the invention, a desirable practical embodiment thereof will now be described in by way of atypical illustrative example. Such embodiment is illustrated in the accompanying drawings, in which,

Fig. 1 is a diagramof suitable apparatus for practicing the novel method of charging and sealing the tube.

Fig. 2 is a side view of a finished circuit breaker, partly in section;

Referring to the drawings in detail, and fifstto Fig. '2, the finished device made in accordance with my improved process is in. the general form of a standardaudi'on tube,

in which 1 is the envelope or tube of glass mounted on a standard base 2, carrying terminal contacts 3-4 adapted cooperatively to engage with a standard audion tube socket, not shown, for the purpose of connecting the terminals with an external circuit. The mechanical parts are. mounted within the tube by means of the stem or press seal 5 through which the conductors enter the tube and are sealed. These parts consist of the stationary contact members 6, most desirably of tungsten, mounted on and electrically continuous with the bracket 7, the lower portion 8 of which forms the lead-in conductor for the contact 6. The movable contact 9, also most desirably of tungsten, is carried by the vibrating arm 10 pivoted at 11 in the bearing post 12 mounted on the bracket 13, the lower portion 14 of which-forms the lead-in conductor for the contact 9. A retractile spring 15 is connected between the bracket 13 and arm 10 to normally hold the contact 9 in engagement with the contact 6 under tension. The arm 10 is made of magnetic material, such as soft iron, and forms the armature of an electromagnet, the other parts of which are not shown but which it will be understood are situated externally of the tube and arranged when energized to pull the arm 10 to the right against the tension of the retractile spring and to open the contacts 6-9.;

the magnetic field operating through the glass walls all in a manner well understood in the art to which the invention pertains.

Filling the tube and surrounding the contacts and other mechanism therein, is a suitable inert gas, under .superatmospheric pressure in the specific example here illustrated. By the term suitable inert gas is meant such gas as will not combine chemically with the material of the contact members. Among suitable inert gases are argon, nitrogen and carbon dioxide. In the present example argon is employed. The tube thus formed is sealed near the base at 16 so as to leave the tube smooth and round at the top portion for a purpose which will appear in the following disclosure of the method of charging and sealing.

Referring how to Fig. 1, which shows the apparatus used in charging, a valve pipe 17 leads from a source of gas supply, not shown, to the bottom of bottle 18 containing a deoxidizing agent, such as a solution of pyrogallic acid, while the top of the bottle is connected througha valved pipe 19 to the lower or inlet end of an arrangement of drying tubes 20 containing a suitable moisture absorbing compound. The upper or outlet end of the drying tubes is connected through a valved pipe 21to the inlet end of an arcing bottle 22. This consists of a glass chamber in which is mounted a pair of spark or arcing terminals 23 connected through conductors .24 to a suitable source of high potential cur-' rent 25. A bulb 26 of about 1,000 cc. capacity is connected through the valved pipe 27 wit the upper or outletend of the arcing bottle and provided with a manometer or pressure gauge 28 connected to indicate the pressure in the bulb. The bulb 26 is also connected through a valved pipe 29 to the T connection 30 to the central member of which is connected the filling tubulation 16 of the circuit breaker tube 1 to be charged, while the right band member is connected through a valved pipe 31 to the vacuum pump 32. A Dewar flask 33 containing a cooling agent, liquid air in the present example, is arranged to receive the rounded or top end of the tube 1. The valves or stop-cocks for the different pipes are indicated at 34, 35, 36, 37, 38 and 39. The method of charging and sealing is as follows: The entire apparatus is first evacuated by operation of the vacuum pump 32 with all stop-cocks opened beyond Stopcock 37 is now turned to close pipe 27 and argon gas is admitted under pressure throu h pipe 1 gas is caused to first bubble through the pyrogallic solution in the bottle 18 to remove any oxygen contained in the gas, and then passes through the drying tubes 20 into the arcing bottle 22. The arcing bottle 22 having been filled with argon to a considerable pressure, say 30 to 40 pounds, the valve 36 is closed and the arcing bottle operated to purify the contained argon by maintaining an electric are 23 therein for a considerable time, say 24 hours. The gas now being of sufficient purity to be used in the circuit breaker tube, the valve 37 is o ened while maintaining the valve 38 in plpe 29 closed andthe gas ad. mitted into the bulb 26 to a predetermined pressure as indicated by themanometer 28, and consequently to a predetermined amount, after which the pipe 27 is closed. The circuit breaker tube 1 Is now connected, as shown, with the'valve 39 open, and the pump 32 operated to exhaust the tube 1 to a good vacuum of the order of .001 mm. of mercury, whereupon the pump is shut ofif by closing the valve 39, and gas from the bulb 26 admitted into the evacuated tube 1 by opening valve 38. The'Dewar flask 33 is now raised into the position shown in Fig. 1 to partially immerse the tube in the liquid air. As the tube 1 by opening stop-cock 34. Thus t e cools to liquid air temperature, argon is liquefied in the tube 1, and the pressure in the system between valves 37 and 39, including the bulb' 26 and tube 1, drops a definite amount. The amount of gas condensed in the tube 1 depends upon the pressure in, and I tain, in the finished tubes, gas pressures of .tube at ordinary room any desired magnitude. In the present example the gaseous pressure in the finished temperature is assumed to be about three atmospheres, (i. e. about pounds above atmospheric) which is adequate in many typical cases although higher or lower pressures are sometimes desirable and are readily obtainable. As a rule it is ordinarily desirable in practice that the pressure be at least about 30 pounds above atmospheric.

It is pointed out, however, that sealing may be done without actually effecting either liquefaction or solidification where the nature of the gas used is such that reduction of pressure by cooling or refrigeration can be carried to a point suflicient to permit sealing.

While, for the purpose of disclosure, I have shown and described the invention as carried out in the manufacture of a vibratory circuit breaker, it is to be understood that it-may be applied to any sparking device where quenching the spark or the prevention of oxidation of the electrodes is desirable.

' It is to'be noted that the invention is not limited to methods of manufacturing circuit breakers, but relates broadly to gas filled envelopes and methods of making the same irrespective of their use.

,It is also to be understood that the inven: tion is not limited to the specific applications herein cited but contemplates all suchmodifi cations and variations as fairly fall within the scope of the appended claims.

,What I claim is:

1. The method of manufacturing a quenched spark gap device which comprises mounting the spark gap elements in an envelope with leads extending therefrom through the walls of the envelope and hermeticallyseal ed therein, charging the envelope with condensed gas, reducing the pressure within the envelope while maintaining the quantity of condensed gas constant, and sealing ofi the envelope.

2. The method f manufacturing a quenched spark gap device which comprises mounting the spark gap elements in an envelope of glass'with leads extendingfthere from through the walls of the envelope and sealed therein in direct contact therewith. charging the envelope with'a given quantity of condensed gas, reducing the pressure within the envelope below atmospheric while maintaining the quantity of condensed gas substantlally constant, and sealing the envelope by welding. .r t

welded. seal, which comprises charging the envelope with gas while refrigerating the same within the envelope to condense it at least partially to a non-gaseous state, ex-

. hausting the envelope to reduce the ressure' below atmospheric while maintaining the contained gas in condensed form, and sealing the tube by welding.

4. The method of obtaining a weld sealed envelopefilled with gas under :superatmos pheric pressure which comprises lacing the gas within the envelope in liquid form, exhausting the envelope to maintain the pressure therein below that of the atmosphere and sealing the envelope during the maintenance of such low pressure.

5. The method of obtain'in a weld-sealed envelope filled with gasun er superatmospheric pressure which comprises placing the gas within theenvelope in liquid form, refrigerating and exhausting the envelope to maintain the pressure therein below that of the atmosphere 'and sealing-the envelope during the maintenance'of such low pressure.

6. The method of obtaining a weld-sealed envelope filled with gas under pressure which comprises charging the gas into the envelope and refrigerating the same to liquefy the gas, maintaining the gas liquid by continued re- -frigeration while exhausting the envelope to p prises subjecting the argon to the action of a deoxidizing agent, drying the argon, purifying the same by the action of an electric d18- charge, charging a -predetermined quantity of said argon into a reservoir at a predetermined pressure, connecting the envelope with the reservoir through a charging tube integral with the envelope, refrigerating the envelope until the pressure is reduced to a desired extent, disconnecting the charging tube from the reservoir and exhausting the envelope through the charging tube to a pressure below atmospheric while maintaining the contained gas in condensed weld-sealing the tube.

8. The method of obtaining a glass envelope filled with a gas under pressure and sealed by welding which comprises evacuating the envelope through a tube integral therewith to a high degree of vacuum, conform, and

necting the envelope through the-same intedense the gas therein at least partially to a thetube and contents to con-' non-gaseous state, again connecting the envelope through the same integral tube with the vacuum pump and exhausting the en-.

velope to a pressure below atmospheric while maintaining the quantity of condensed gas constant, and sealing ofi the integral tube.

9. The method of obtaining'an envelope fillecl with a gas under pressure which comprises e'xhausting the envelope to a high degree of vacuum, providing a quantity of gas in the envelope condensed by refrigeration and sufiicient in quantity to reduce in the envelope a gaseous pressure 0 at least lbs. per square inch at a selected temperature, exhausting the envelope to a pressure less than atmospheric, sealing the envelope by welding, and permitting the Whole to rise to the selected temperature.-

In testimony whereof I hereunto ailix my signature.

RAYMOND ROBERT MACHLETT.

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